Isil has just unleashed a deadly chemical cloud which could make Mosul ungovernable

Fighters of the Islamic State of Iraq and the Levant (ISIL) celebrate on vehicles taken from Iraqi security forces, at a street in city of Mosul June 12, 2014Credit:
Stringer/Iraq

As predicted, and generally expected, Isil set fire to the Mishraq Chemical plant and sulphur mine 30 km south of Mosul on Thursday last week as they fled towards the city. To date, up to nine people have died and around 1,000 have been injured, including foreign journalists.

The toxic cloud, which includes deadly sulphur dioxide and hydrogen sulphide, combined with residue from burning oil wells, is a potentially fatal cocktail for those caught in the open or without gas masks.

It currently stretches 20-30 km to the south over sparsely populated ground, but if the wind changes to blow to the east, as it usually does at this time of year, there is a slim chance that the Kurdish capital Erbil, 60 km away, could come under threat.

Mishraq is the latest step in Isil's plan to defend Mosul, at all costs, with all weapons available. It is no surprise that the ultimate terror organisation is looking to the ultimate terror weapon, chemicals, to save the Caliphate HQ. Chemical weapons have kept Assad in power a number of times in the last three years, and are highly effective in defend built up areas and cities.

Assad was about to be overrun in Damascus by rebels in August 2013. He had fought them conventionally for two years, and on the point of defeat he used up to 1000kg of the deadly nerve agent Sarin.

This stopped the rebels in their tracks, killed up to 1500 (mainly women and children as they slept in their beds), and created inertia for demonstrative action in Syria by the international community which pervades to this day.

They are making mustard agent (gas) in Mosul and have an almost limitless amount of chlorine to fill into mortars, which they’ve used to attack the Peshmerga for the last 12 months, and IED’s – I personally witnessed one such attack at Gwer in April this year.

The use of hundreds of chlorine IEDs to defend Tikrit in April 2015 severely slowed the advance of the attacking Iraqi Army. The Coalition have successfully targeted the Isil chemical programme, and killed the senior scientist Abu Malik in an air strike in March 2015, while US Special Forces captured other key men later in 2015, but it is still intact.

What is clear is that, though crude, Isil's chemical weapons programme is extensive and could be a key tool in the defence of Mosul.

Watch | Soldier's body cam captures fight against Isil

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Attacking towns and cities is notoriously difficult and the advantage is generally with the defender. Almost one million Germans failed to take Stalingrad in WW2 and the might of Russia and the Syrian military is failing to take eastern Aleppo from a few hundred rebels.

Although these are not direct correlations, if you can get the attackers to wear gas masks it makes the fighting even more difficult, or if you can use chemical weapons against attackers with no gas masks, they may lose the will to continue the fight.

I have no doubt the Peshmerga and the Iraqi Army will prevail in Mosul and liberate this city from the clutches of Isil. But they need to be prepared and enabled by the Coalition to combat chemical attack, as will the NGOs and aid workers who must flood into the City as soon as it is liberated.

It is not good enough to walk into another Mishraq type event and be surprised when Isil do what we expect them to do however abhorrent.